1/2 VW Best plans? Cut case?

[83462]

I am very interested in building and Eagle but don't really have the room or the time right now.  I figure I could probably settle for just focusing on the engine right now.  I mostly do my own auto work... brakes, radiator and other easy stuff but I have never really taken an engine apart.

Should I focus on some minor tasks first before attempting a 1/2 VW conversion?

Which is recommended?  Cut block or not and why?  Any particular plan to purchase?

Any good books?

[Bob S.]

I say full case, but everybody has their ideas... Why cut and remove a perfect engine mount only to have to make a new one??
BUT if you are going for a magneto, then I can see why... It can be done with a full case, but you have to modify the firewall.... Always some compromises....

[83462]

How about the weight limit?  Is that a real consideration between the two?  Thanks!

[Sam Buchanan]

With your limited shop background the full-case engine would be the best option. It involves much less machining and as stated above you don't need to build a mount. The total-loss battery ignition works fine for our short duration flights and is easy to set up and maintain.

However....by the time you add up the $$$$'s of all the new after-market stuff you need for either engine, it is hard to justify building instead of buying a ready-to-fly engine from Hummel (Casler). There are very few stock VW parts in our engines.

[Bob S.]

Well, I have a full-case on my LE and the ONLY NON-stock item is the valve push-rod hole plugs and the plate over the old gen-tower.... I made those... The crank, heads, valve covers, rocker shafts and cam are modified stock items. Unless you go with the Nickies the pistons and cylinders are "stock" (over-size) VW parts. The connecting rods & oil pump are usually stock....

There is no real significant difference in weight...... what you cut off the case, you have to have an Aluminum plate to close the back of the cut case and add a mount, most likely steel.... so you add most if not all back on...

[Sam Buchanan]

Bob, thank you for reinforcing the point I made.  

As you stated, there are very few stock, unmodified parts in our engines. This is especially true if you run one of the big bore/stroke engines. The only standard VW parts in my 45 are the rocker arms, timing gears and oil pump. Everything else is either race aftermarket or modified.

[Dert Merchant]

I'm glad this question came up; I was going to ask the same one. Instead I'll just piggy back onto it. Are these engines along the lines of buggy engines where the theory of "there's no replacement for displacement" is the order of the day? The reason I ask was after looking over the "better half" plans and reading the hp numbers for stock crank vs. a stroker crank.

[Bob S.]

I'm glad this question came up; I was going to ask the same one. Instead I'll just piggy back onto it. Are these engines along the lines of buggy engines where the theory of "there's no replacement for displacement" is the order of the day? The reason I ask was after looking over the "better half" plans and reading the hp numbers for stock crank vs. a stroker crank.

 
You are mostly correct.... As you will notice most of the "Big Dogs" flying the Legal Eagle have gone to the Casler big 45...Big bore, stroked crank but light with Nickies. I have a NICE engine, not too big, pulls me around nice although I haven't tried the hot weather flying down here in San Antonio, TX with it....It's 92 x 78. I believe the 94 jugs might be asking for a hot running engine with the thin walls. Must be different with the Nickies as that is what Scott Casler has on the 45 (hp) and a bit more stroke I believe..... Use as big as you can afford. but no sense going overboard if you don't need to. Modified too much like a big buggy engine where you make all your HP at high RPM is NOT what you want... You need a good, strong, DEPENDABLE Tractor Engine! Make your HP at around 3600 RPM max to keep prop tip speeds with in reason and less than supersonic!!

[Sam Buchanan]

I'm glad this question came up; I was going to ask the same one. Instead I'll just piggy back onto it. Are these engines along the lines of buggy engines where the theory of "there's no replacement for displacement" is the order of the day? The reason I ask was after looking over the "better half" plans and reading the hp numbers for stock crank vs. a stroker crank.

Even though the 94x86 45hp engine is now in sorta common use on the XL's, the smaller 37hp engine will fly it very nicely. The 37hp is less money and a smoother engine. But the 45 is actually two different engines depending on how it is configured with carbs and prop. With dual carbs it can develop rated power--with a single carb it is a torquey, lower rpm engine that works great if max climb isn't part of the mission profile.

We have choices.